Process for producing electrodeposited nickel strip containing boron



Patented bee. 14 1948 PROCESS amt 1 anomalies 1 acne-deans,

stair -.CONIAEINJNG BQSIZLED NICK-EL BoRoN.

Montimer- Pierce Buck,

tyingagents to the molten metal. Thus, in :pro-

Huntington; WnVa -'as=- signor .to The International Nickel Company, .llnc.,zNeyv Honk, K, a ccnnoraticniotflelaware Nbp e in Application April 16;;19 15, Serial Ne.

- 587,024. IrrCanada Fehruary 19, -1945 Lia-Giants. (oil-enact) ducing alloys of metals electrolyticallyproduced; 7

it has been necessary to ladd' deoxidizers, -.desul-' furizers, hardening iagents, agents for increasing the tensile strength, agents :for inducing :precipi tation *hardening and theilike to :a molten charg of the electrolytically produced metal.

In many instances, even when it has not been deemed necessarylor desirable to-add modifying agents, the fabrication of electrolytically produced metal has .been attempted with difficultyl An example o-fthe difiiculty encountered in directlywutilizing electrolytically:produced metal is the'ldifiiculty arising in-attempting to produce nickel strip directlyirom 'nickelxcathodes, The art has been confronted with the problem of pro;- ducing nickel strip directlyirom cathode nickel :without the formation OflbliStBPS son. -:annealingl The art recognized the broad problem $.as early as 19-21 as :jwill zbe-readilywunderstood :by a reference to U.1S.Patent-No. 1;628,14l9.grantedtorHybinette. This patenteerproposedato;make.:malleable nickel directly riromacathode nickel 1by rolling; and annealing the .cathodeunickel thus -produced. An important feature ohHybinettes process was .the

boiling of the electrolyte in such a mannerithat the total volume .of electrolyte. employed "was boiled at least oncezever y z i hours. Later, 'UI-S. PatentNo. 2,181,936 was granted :to Glappier and McDowell on a process for producing nickel strip directly from cathode nickel. The Clappiemand McDowell process involved :cold rolling, annealing at critical temperatures and-subsequent iurther reduction of the-annealed strip to final gauge.

It will be observed that thelatter'of these patented processes seek during the rolling to-correct a condition existing in'the metal'delivered to the rolling mill which appeared to be the cause of the blisters in the finished nickel strip. It has now-been discovered that-blister-free nickel strip can be produced directly from cathode nickelby eliminating the source of the difliculties before the cathodenickelis introduced intc therolling mill.

such modifying or addition agents 'as are necessary' :toiproduce :the desired. finished product.

it Lia-within .the purview .of the present invention to provide a process sior introducing modi iyi-ng .or; addition agents such as deoxidizers, desuliurizers, hardening lagents agents tor increasing tensile strength and .the like into cathode metal attemperaturesloelow the fusion point of the icathode'imetal.

The present invention likewise-contemp1ates a process for: producing. blister-tree nickel strip mhereinzdegasifiymg agents are introduced into the nickeLcathodeebeiore reduction in gauge.

Other objects :and advantages will become apparent fromthe-lfollowing description.

Thisapplication is lascontinuation-in-part of my cpepending 2U. 18.. application Serial :No. 382,- 164,;filed Marchfl, 71941, which hastbecomelaban- .donedll E ,iBroadly speaking," the :present. invention "in.-

, values thedntroductionofjan l elemental modifying agent into one lorpmore portions of .a metallic product, atgleasta part :Qf which :is z cox nposed lof electrodepositedmeta1,:f0llowed by heat treat- .mentto thenebyrcauseldifiusion oi said modifying la en dnto themest of saidsinetallic product. The modifying aeentrmay belintroduced into the electmdenasi ed .imeta-l during .one or moize-of :the electrolysis steps .or itmaybe included in .a non? .electsodeposited {portion :of the metallic product. Al ernatively,thednodifyineagennma zbela lied othe sur iace of said metallic product .in one or #1 91 f aee xofthe preparation :thereof. After It is an object of thepresentinvention'to pro Vide cathode metal having incorporated therein ntr duct on of he modifying agents thelmetauic product is .ihealt :treated at elevated itemperatures horizontally sin a platingtankiand the elemental modifying 'agent suspended :in the plating path causing the particles of the modnyinglagent to settle upon athetstartingt sheet.i After electrolysis, the modiiy-ing agent is thus includedr between :=the starting'sheet and the Lelectrodeposited metal. It is also within .tne purviewrof thednventiomw cQ- face of the cathode and go into solution in the I cathode metal with resultant diffusion into the interior of the cathode due to the elevated temperature of the molten bath. On the other hand, the modifying agent may be dissolved or suspended in a molten bath from which the metal is deposited.

In another embodiment of the invention, the modifying agent may be introduced into a nonelectrodeposited starting sheet. The desired amount of metal is then deposited upon the starting sheet by conventional methods. embodiment of the invention, the elemental modifyin agent may be added to the starting sheet when the latter is in a molten condition or the starting sheet may be formed by the conventional methods of powder metallurgy from a mixture of powdered metal and modifying agent.

The modifying agent may also be applied to the surface of the metallic product during one or more stages in the formation thereof. Thus, the molten modifying agent may be applied to the surface of a starting sheet and metal plated thereon after the modifying agent has solidified. Alternatively, the vapors of the modifying agent or a suitable compound thereof, such as the hydride, may be sprayed upon the surface of the starting sheet prior to deposition. It is also within the scope of the invention to interrupt the electrodeposition at intervals and apply the molten modifying agent to the surface. Equivalently, the vapors of the modifying agent or a suitable compound thereof may be sprayed upon the surface when the deposition is interrupted.

The metallic product containing the elemental modifying agent produced by any of the methods hereinbefore discussed is then worked to desired gauge and subjected to heat treatment at elevated temperatures with resultant desired change in the physical and chemical properties thereof. As an illustration of the principles of the present invention, the introduction of elemental boron into nickel strip may be considered. I have discovered that nickel strip containing elemental boron is substantially blister-free when exposed to temperatures in excess of about 1000 F. whereas ordinary electrolytic nickel strip is badlyblistered after exposure to such a temperature.

The elemental boron may be introduced into the nickel by any of the methods referred to hereinbefore. However, I prefer to suspend powdered elemental boron in a conventional nickel plating bath from which at least a portion of the nickel strip is deposited. The amount of elemental boron to be added may vary from about 0.0001 ounce per gallon to about 0.02 ounce per gallon. The use of a greater quantity is uneconomical. Moreover, if a greater quantity is used, the elemental boron tends to interfere with the deposition of the nickel from the plating bath.

On the other hand, the use of a lesser amount results in blistering of the nickel strip when exposed to temperatures above about 1000 F.

The batch is agitated during plating in order to keep the particles of elemental boron in suspension. Preferably, a stream of compressed air is blown through the bath during the. deposition oftheanickel, although stirring or. mechanical In this throughout the electrodeposited metal.

agitation ma be utilized. I have also found it helpful to oscillate the cathode while nickel deposition is occurring. In the event that it is not desired to agitate the bath, a starting sheet may be placed horizontally in the electrolyte and the particles of metallic boron allowed to settle thereon. Nickel may then be deposited upon the starting sheet, thus entrapping the elemental boron between the starting sheet and the electrodeposited nickel.

It is to be understood that the present invention embraces the inclusion of elemental boron either in a portion of the electrodeposited metal or Thus, nickel may be plated upon a commercial nickel cathode from a conventional plating bath to which elemental boron has been added. Alternatively, nickel may be deposited upon a starting sheet from an electrolyte having elemental boron suspended therein. If desired, deposition may be interrupted when not less than 0.003 inch of nickel has been plated and deposition continued in a bath free from elemental boron until a deposit of the desired thickness has been built up. For best results the thickness of the cathode after electrodeposition should be from about 0.050 inch toabout 0.250 inch.

After the desired thickness has been attained, the. cathode is removed from the bath and annealed for the purpose of diffusing the metallic boron throughout the body of the cathode. The time and temperature of the anneal will depend on the method used to incorporate the boron in the cathode. If the boron has been deposited throughout the cathode, an anneal for about to about 2 hours at a temperature of about 1500 F. to about 2400 F. is preferred. If the boroncontaining nickel plate is only a small portion of the entire cathode, then an annealing treatment of about 4 to about 16 hours at a temperature of about 1500 F. to about 2400 F. is preferred. Those skilled in the art will appreciate that an annealing period of about to about 16 hours may be utilized, the length of the period depending on the thickness of the b0ron-containing plate as compared with the total thickness of the cathode from which the nickel strip is to be produced.

If the boron-containing plate is deposited on the surface of a boron-free cathode, some precaution must be taken to avoid the loss of boron during the anneal. The cathode may be provided with a gas-tight envelope during the annealing treatment or, alternatively, a protective atmosphere maybe utilized. A protective atmosphere, in this sense, is one which is inert or nonoxidizing with respect to the modifying agent, for example elemental boron, which is used. However, if the boron has been deposited throughout the cathode or if the boron-containing plate has been overlaid by a boron-free nickel plate, such precaution need not be observed.

After annealing; the cathode is hot or cold worked to produce a reduction in thickness of at least 20% and preferably at least 50%. It is notable that this reduction in thickness is accomplished without edge checking or other difficulty- The nickel strip produced in accordance with the principles of the present invention has a'ductility of about Erichsen to about 105 Erichsen, a value of being taken as the average value for annealed nickel. Furthermore, the nickel strip is substantially free from blistering when exposed to temperatures in excess of about'1000",F. W

amaze:

Itds :nnportant thatthe'horonywberdepositedan elemental storm iin order ".to obtain thezvznovel. re:- snltsaof the present invention. Iram aware that a small quantity oflzborates is: usuallyapresent in nickel deposited rtrom rconventional rniekel plating baths in which boric sacid-fis used as "a butler; Howevenntheihorates .arez: only :present "intspectnoscenic uantities, vii i at 4 all; and the: presence-of borates: rim stripcxdoesmotrprenent senere blistering thereof when EBXDOSBd 'tO'FtHIIlDEIEBItIH BS in-iexcess :ofxabent 1x099 F .Thus,:aznickel!cath+ ode plated from :a conventional nickel plating bath'eontacining approximately :30 grams periliter of boric :acid, "cold ironed to ia thickness ofsabout 0.020 inch and: annealedat a temperature 0f about 2200" F. developed from about 520 to about H30 lblisters per' square toot upon subsequent exposnre to temperatures of excess of about 1000 F.

Cathode strip containing elemental boron and produced: as hereindescribed when exposed "to temperatures appreciably in excess of 1000 F; after hot or cold working to relatively thin sections or gauge is. blister-freer Relatively thin cathode-nickel produced as describedherein without -hot or cold working, that is to say directly; when exposedto elevated temperatures in excess-of 1'000-F."is likewiseblister-free;

A hypothesis -explaining-the novel results obtained by employing the "process- 'of "the present invention in the production of 'blister free oathode nickel strip, for example, predicates the existence of oxygen-containing occlusions "in the electrodeposited metal such as water, either free or in combination, hydroxides and oxides.- When such cathode metal is heated to elevated'temperatures these occlusions liberate water vapor, or unite with occluded hydrogen 'to iormfwater vapor. The steam pressure thus generated-is suficient to produce blisters. However; when boron is incorporated in cathodejmeta'lin accordance with theprinciples of the present" invention, it may be predicated that the'boronnnites with the oxygen forming a compound which does 'not' decompose at temperatures to 'which the cathode strip is subsequently exposed. 'Thus,'the oxygen is present in a heatistable forminstead of in a heat labile form and the hydrogen liberated by this {reaction -,escapes from the cathode'by diffusion.

The 'folliowingdllustrative examples are provided' for the purpose of giving .a person skilled in the "art adlearundeistandirigofthe method'of practicing my invention:

Example I A; commercial Qnickel cathodewas suspended in a -.conventional Watts nickel plating bath'to which about 10,014 ounceper gallon of elemental boron wasadded; The elemental boron wasskept in suspension during. the plating .by agitating .the

substantially nee tdrom @bnstennewhenexposed to temperatures higherflathan. about M00 F, Analysisiofs-thelcathode heioreuelectnodeposition revealed presence-piano eelementa'l heron.

Example 1.

A p ss v star nessheet W $1$1 Pfind i=m conventional nickel plating electrolyte to which about "03),l4oun'ce per gallon of elemental boron was added. "Plating was carried out at atom.-

perature pfwaboiit 130 F., a p'Hrof abOll-tfilflanda current density of about 5'7 amperesper square foot. "Ihe bath was agitated to insure that the metallic boron would remain in suspension. When -;the :deposit-ihad-zattained a tm hness o about new inch, the cat ode was r moved the electnoplat ahaith and'the boron-. e;o nta;ing nickel plate IjS'bl ped 1-fr0m the passi-ye star ng hee The sh etofabo onw taininse e trol ie nickel thus obtained was plated on both sides :in a. secondniclsel platin -electro1ytewhich osmtainedinoelemen al:boronuntiharto thi kness of abont ilflzfinch was attained-n Ehe athodewas removedirom the bathand a-heat treatcdvifort about 1 and hours at a tempenature of about: 22598 Theacathode was then ncold vqnol'led rto a thickness aof about rfiifizihinch aandnupon analy s was-found to,=containzab;ont 0.005%:boron. :Subr; stantial :Ereedom from :hli'stering was, :ohserned when :said :cathode minkel u strip was exposed the temperaturesiinexoess 'of albout 1000" :'F.

Example TILL Amickel starting-sheet was cathodicallymreatecl in a conventional Watts hath-to wl-iich abont o liltll i ounce per gallon ofelemental boron *was added; v A temperature oi about lw 'F a pH of about and acurrent density of about amperes'per: square foot were maintained during the electrolysis which was continued until -apla ing abQut- OZl-B- inch thickwas' obtained. -Gontinuous agitation with "compressed air was u i liz'ed throng hout the eleetrodeposi tion to' keepthe" elemental boron in suspension in the-plating tank. Theeathode was removed from' the bath and subjected to diiiiusion for about -one halfhour 'at a temperature -of "about 2 1110 Tl iel cathode was then coldrolled to'a thickness of about 02020 to :I'orm nickel strip \nrhic'h ana- 1-yzed-about-'0;02 elemental heron." When the nickel strip wassuhjected to temperatures i-nexcess-of about 1000 'Fi, substantially mo -blistering waspbserved; 1 The blister-free nickel strip -produced :as 2 lie-- scribed imthe preceding.examples hada ductilityof -betwe'en about -Ei ichsenand about 1 05 Er ichsen, avalue -of 1'00 being talcen as the average value for anneailed niokel;

Although the pnesent invention has been describ'ed in con j unctionwith certainembodiments thereof, it is tobe- -u'ndensteed that variations and modifications-may be made as thoseskilled' inwthe artwillsreadily nnderstand. Such =va1 iations and modifications are to be considered within ithe Lpu-nniew of the .-specification aand the scoperofzthelappended -claims. while mentionfzhas :been .made of boron; iitiis -tohe' understood that zby zthe. term modifying': or addition agent i :or .materials such el'erne'n ts as carbon, lithium, benyllium, sodium, :magnesium, alnrrii num, @sil-ico'n, phosphorus; potassium; calcium, scandium, titaniumnvanadium, chromium manganese, rubidium,;-strontium,' "yttrium; zirconium, colnmbium, molybdenum, cesium, barinm; 1am thamimandlthe 1 other -rare earth elements, haibnlum, tantalum, tungsten, bismuth, thorium'and uranium are also included.

Furthermore, as those skilled in the art know, the Watts bath is the conventional bath presently used for plating nickel. A typical Watts bath has the following composition and is operated under the following conditions:

Nickel sulfate; oz.'/gal 32 Nickel chloride do 6 Boric acid; do 4 pH (electrometric) 1.5-3.0 or 4.5-5 6 Cathode current density amp./sq. ft Temperature F 110 therein, stripping said layer of nickel from saidstarting sheet, plating nickel upon said layer of nickel from an electrolyte containingno elemental boron until a thickness of about 0.050 inch to about 0.250 inch is obtained, annealing the resultant cathodic electrodeposit for about hour to about 2 hours at a temperature of about 1500 F. to about 2400 F., and working said cathodic electrodeposit to reduce the thickness thereof at least 20% to produce e1ectrodeposited nickel strip having substantially no tendency to blister when exposed to temperatures in excess of about 1000 F., said electrodeposited nickel strip having a ductility of about 90 toabout 105 Erichsen, a value of 100 being-taken as the average value for annealed nickel.

2. A process for producing electrodeposited nickel strip containing boron which comprises plating a layer of nickel having a thickness of at least 0.003 inch upon a starting sheet from an aqueous nickel plating bath containing. about 0.0001 to about 0.02 ounce per gallon of powdered,

elemental boron, agitating the bath during plating to maintain said elemental boron suspended.

therein, stripping said layer of nickelfrom said starting sheet, plating nickel upon said layer of nickel from an electrolyte containing no elemental boron until a thickness of at least0.050

inch is obtained, heat treating the resultant;

cathodic electrodeposit for about hour to about 2 hours at a temperature of about 1500 F. to about 2400 F., and Working said cathodic electrodeposit to produce electrodeposited nickel strip having substantially no tendency to blister when exposed to temperatures in excess of about 1000 F.

3. A process for producing electrodeposited nickel strip containing boron which comprises electrodepositingnickel on a nickel cathode from an aqueous nickel plating bath containing about 0.0001-to about 0.02 ounce per gallon .of ele-.

mental boron, agitating said plating bath to maintain the elemental boron suspended therein while oscillating said nickel cathode, removing saidcathode from the electrolytic bath when a: thickness of at least 0.050 inch'is obtained, heattreating said nickel cathode for about hour to about 2 hours ata temperature of about 1500" F. to about 2400 and working said nickel cathode to obtain electrodeposited nickel strip having substantially no tendency to blister when exposed to temperatures in excess of about 1000 F., said electrodeposited :nickel strip containing about 0.001% to about 0.02% of elementalboron.

4. A process for producing electrodeposited nickel strip containing boron which comprises depositing nickel on a nickel cathode from an aqueous nickel plating bath containing about 0.0001to about 0.02 ounce per gallon of elemental boron, agitating said plating bath to maintain the elemental boron suspended therein, removing said cathode from the electrolytic bath when a thickness of at least 0.050 inch is obtained, heat treating said nickel cathode for about A; hour to about 2 hours at a temperature of about 1500 F. to about 2400 F., and working said nickel cathode to obtain electrodeposited nickel strip having substantially no tendency to blister when exposedto temperatures in excess of about 1000 F.

5. A process for producing electrodeposited nickel strip containing boron, said nickel strip having substantially no tendency to blister when exposed to temperatures in excess of about 1000 R, which comprises electroplating at least 0.007 inch of nickel upon a nickel cathode from an aqueous nickel plating bath containing about 0.0001 to about 0.02 ounce per gallon of elemental boron, passing a stream of compressed air through said plating bath while the nickel is being deposited, heat treating the resulting nickel electrodeposit for about 4 to about 16 hours at a temperature of about 1500 F. to about 2400 F., and working said nickel electrodeposit to produce nickel strip substantially free from volatile heat labile compounds of oxygen, sadi nickel strip having a ductility of about to about'105 Erichsen, a value of being taken as the average value for annealed nickel.

6. A process for producing electrodeposited nickel strip containing boron, said nickel strip having substantially no tendency to blister when exposed tov temperatures in excess of about 1000 F., which comprises immersing a nickel cathode in an aqueous nickel plating bath containing about 0.0001 to about 0.02 ounce per gallon of elemental boron, electroplating at least about 0.007 inch of nickel from said plating bath, agitating the bath while the nickel is being deposited therefrom, annealing the resulting nickel electrodeposit for about 4 to about l6 hours at a temperature of about 1500 F. to

about 2400" F., and rolling said nickel electrodeposit to produce nickel strip substantially free from volatile heat labile compounds of oxygen.

'7. A process for introducing boron in elemental form into a nickel product, at least a portion of which is composed of electrodeposited nickel, which comprises introducing about 0.0001 to about 0.02 ounce per gallon of powdered elemental boron into an aqueous nickel plating bath from which at least a portion of said nickel product is electrodeposited at .a cathode im-. mersed therein, agitating said plating bath to maintain said boron suspended therein, heat treatingsaid nickel productv at a temperature of at least 1500" F. for at least /2 hour to thereby cause diiiusion of said elemental boron throughout said nickel product, working said nickel prod-' uct to desired dimensions. and annealing said productat a temperature above about 1000 to obtain a ductile, blister-free nickel produced without melting.

8. A process for introducing boron in elemental form into a nickel product, at least a portion of which is composed of electrodeposited nickel, which comprises suspending about 0.0001 to about 0.02 ounce per gallon of powdered elemental boron in an aqueous nickel plating bath from which at least a portion of said nickel product is electrodeposited at a cathode immersed therein, agitating said plating bath to prevent settling of said elemental boron, and heat treating said nickel product at a temperature of at least 1500 F. for at least /2 hour to thereby cause diffusion of said elemental boron throughout said nickel product, working said product, and annealing said product at an elevated temperature to obtain ductile, blister-free unfused nickel. i

9. A process for introducing boron as a modifying agent in elemental form into a nickel product, at least a portion of which is composed of electroplated nickel, which comprises suspending about 0.0001 to about 0.02 ounce per gallon of powdered elemental boron in an aqueous nickel plating bath from which at least a portion of said nickel product is electrodeposited at a cathode immersed therein, and heat treating said nickel product at elevated temperatures to thereby cause diffusion of said elemental modifying agent throughout said nickel product, thereafter subjecting said nickel product to mechanical working and then subjecting the mechanically worked nickel product to an annealing operation to produce wrought nickel substantially devoid of blisters without resort to a melting operation. 7 i

10. A process for introducing boron as a modifying agent in elemental form into a nickel product, at least a portion of which is composed of electrodeposited nickel, which comprises introducing about 0.001% to about 0.02% of elemental boron into at least a portion of said nickel product, while electrodepositing said portion from an aqueous nickel plating bath wherein about 0.0001 to about 0.02 ounce per gallon of powdered elemental boron is suspended and annealing said nickel product at elevated temperatures to homogenize said nickel product, and thereafter subjecting said nickel product to mechanical working and to the influence of heat to produce a wrought nickel product substantially devoid of blisters without resort to a melting operation. 7

11. A process for producing electrodeposited nickel strip containing boron which comprises electrodepositing nickel to a thickness of at least about 0.007 inch on a section of a nickel cathode from aqueous nickel plating solution containing about 0.001 to about 0.02 ounce per gallon of elemental boron, agitating the plating bath to prevent settling of said elemental boron, oscillating said nickel cathode while the deposition proceeds, heat treating said nickel cathode for about A2 hour to about 16 hours at a temperature of about 1500 F. to about 2400 F. whereby the elemental boron is diffused throughout said nickel cathode, and working said nickel cathode to obtain at least a 20% reduction in thickness to thereby obtain electrodeposited nickel strip having substantially no tendency to blister when exposed to temperatures in excess of about 1000 F., said nickel strip containing about 0.001% to about 0.02% of elemental boron.

12. A process for producing electrodeposited nickel strip containing boron which comprises depositing nickel to a thickness of at least about 0.007 inch on a portion of a nickel cathode from an aqueous nickel plating electrolyte containing about 0.0001 to about 0.02 ounce per gallon of powdered elemental boron, agitating the plating bath to prevent settling of said elemental boron, annealing said nickel cathode for about /2 hour to about 16 hours at a temperature of about 1500 F. to about 2400 F. to homogenize said nickel cathode, and reducing the thickness of said nickel cathode to thereby obtain electrodeposited nickel strip having substantially no tendency to blister when exposed to temperatures in excess of about 1000 F., said nickel strip having a ductility of about 90 to about 105 Erichsen, a value of 100 being taken as the average value for annealed nickel.

13. A process for producing electrodeposited nickel strip containing boron which comprises electroplating nickel to a thickness of at least about 0.007 inch on a portion of a nickel cathode from an aqueous nickel plating bath having about 0.0001 to about 0.02 ounce per gallon of elemental boron suspended therein, agitating said plating bath to maintain said elemental boron in suspension, heat treating said nickel cathode for about /2 hour to about 16 hours at a temperature of about 1500 F. to about 2400 F. whereby the elemental boron is diifused throughout said nickel cathode, and working said nickel cathode to reduce the thickness thereof whereby electrodeposited nickel strip is obtained having substantially no tendency to blister when exposed to temperatures in excess of about 1000 F.

MORTIMER PIERCE BUCK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 211,070 Weston Dec. 17, 1878 850,912 Edison Apr. 23, 1907 1,628,149 Hybinette May 10, 1927 1,795,512 Schmidt Mar. 10, 1931 2,145,745 Armstrong et al. Jan. 31, 1939 2,150,094 Bieber Mar. 7, 1939 2,150,095 Kayes Mar. 7, 1939 2,181,936 Clappier et al. Dec. 5, 1939 2,236,899 Fetz Apr. 1, 1941 2,289,641 Fetz July 14, 1942 OTHER REFERENCES Transactions of American Electrochemical Society, vol. 59 (1931) page364.

Certificate of Correction Patent No. 2,456,370. December 14, 1948. MORTIMER PIERCE BUCK It is hereby certified that errors appear in the printed s numbered patent requiring correction as follows:

Column 3, line 71, for the word batch'read bath; column 5, line 18, for of excess read in excess; column 8, line 40, for sadi read said; column 9, line 59, for from aqueous read from an aqueous;

and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 24th day of May, A. D. 1949.

pecification of the above THOMAS F. MURPHY,

Assistant Uomm'iss'io'ner of Patents.

Certificate of Correction Patent No. 2,456,370. December 14, 1948. MORTIMER PIERCE BUCK It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 3, line 71, for the Word batch read bath; column 5, line 18, for of excess read in excess; column 8, line 40, for sadi read said; column 9, line 59, for

from aqueous read from an aqueous; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 24th day of May, A. D. 1949.

THOMAS F. MURPHY,

Assistant Commissioner of Patents. 

